Graham Warwick/WASHINGTON DC
Next July, five years after it emerged from bankruptcy, New Piper Aircraft plans to deliver the first Malibu Meridian. This single-turboprop business aircraft symbolises the resurgence of a firm that was driven into Chapter 11 by the collapse of the US general aviation (GA) market.
Piper has ridden the revitalisation of the USGA industry and tapped into the buoyant business aircraft market with the Meridian. With orders in hand for over 130 of the $1.4 million aircraft, the company is contemplating an increase in the production rate to accommodate demand.
The basis for the Meridian's design is Piper's Malibu Mirage high-performance piston single, but the structural and systems changes necessitated by the Meridian's still higher performance has resulted in an aircraft that is"75% different", according to programme manager technical Matt Amundson.
While the biggest change is the installation of a Pratt & Whitney Canada PT6A-42A turboprop in place of the Mirage's turbocharged Teledyne Continental TIO-540, the wing and empennage have also been substantially redesigned and the avionics and systems extensively updated.
The PT6 was chosen because of its "fantastic" reliability, Amundson says. The -42 engine has accumulated over 40 million flight hours experience on the twin-turboprop Raytheon Beech King Air 200. For the single-turboprop application, back-up manual fuel control has been added.
The PT6A-42A is capable of producing over 820kW (1,100shp), but is derated in the Meridian to at least 300kW for take-off. This massive derating is required, says Amundson, "because we wanted the aircraft to go fast." The derating ensures that at least 260kW is available at 30,000ft (9,000m), even at temperatures of 10¼C (20íF) higher than standard. Piper is guaranteeing customers a maximum cruise speed of at least 262kt (485km/h).
"Full take-off power is available at any altitude and temperature condition and, at up to 20,000ft, the engine is never temperature limited," he says. The take-off rating that emerges from flight testing is likely to be higher than 300kW, Amundson says, improving take-off and climb performance still further.
The engine will enter service with a time between overhauls of 3,600h, but, if customers choose the optional electronic flight display system (EFDS), this comes with engine trend monitoring, which will allow on-condition maintenance. Operators will download engine data for analysis by P&WC, which will tell them when to overhaul the turboprop. Amundson expects this to extend the PT6's overhaul intervals.
Because a turboprop is less fuel-efficient than a piston engine at lower altitudes, Piper has had to increase tank capacity to 645litres (170USgal). Fuel is stored in the wing and drawn from both sides simultaneously. Balancing is automatic - if the digital engine management system detects an imbalance, electric boost pumps in the tanks bias the flow to restore balance.
Although the wingspan is unchanged from that of the Mirage, leading-edge gloves have been added to increase the area and bring the stall speed down to 61kt at the Meridian's higher, 2,200kg (4,850lb) gross weight. Wing structure is strengthened to cope with the higher loads and speeds.
The empennage is also strengthened, and the horizontal stabiliser increased in size by 37%. The Mirage's "bungee-type" rudder trim is replaced by a dual-redundant electric system. Despite the higher installed power, Amundson says that rudder forces are the same or less than in the Mirage.
The pressurised cockpit and cabin structure is virtually unchanged, but the environmental control and air-conditioning systems are new. Temperature control is automatic, as is the bleed-air conditioning system used for cooling on the ground. The electric system has been upgraded, and now features a 200A starter/generator with 130A standby alternator.
Cockpit changes
Apart from the engine, the biggest change to the Meridian is in the cockpit. Here Piper's philosophy has been to improve situational awareness and ease of operation. The basic "glass" cockpit includes dual Garmin International GNS-530 communication/navigation systems, coupled with an S-Tec System 550 autopilot, and Meggitt Avionics engine display units.
The Meggitt engine instrument display system presents all powerplant and fuel system parameters in analogue and digital format on dual liquid-crystal displays. Databuses connect the engine and fuel system sensors to a data acquisition unit that feeds the displays. Aural and visual warnings are provided if any parameter exceeds limits, Amundson says.
The Garmin GNS-530 includes a 12-channel global positioning system receiver, certificated for instrument approaches, and a large-screen colour moving-map display. Each unit also includes a VHF transceiver providing 8.33kHz channel spacing.
Amundson expects up to 90% of Meridian buyers to specify the optional four-screen electronic flight display system, expected to cost $70,000-100,000. The Meggitt EFDS provides liquid-crystal primary flight and navigation displays for the pilot and co-pilot, driven by dualair data/attitude heading reference systems (ADAHRS).
The Meggitt-developed ADAHRS is the "most advanced technology in the Meridian", says Amundson. The solid-state unit is a repackaged version of a secondary flight display system that Meggitt has certificated and supplied for several other aircraft.
Two of the Meridian prototypes now flying have the full-up electronic instrument system. The first of four prototypes flew in August last year and the fourth was due to fly before the end of September, by which time the first three aircraft had accumulated over 310 of a planned 800-1,000 test flights.
Amundson says the programme is on schedule for US certification and first deliveries next July. Different types of Hartzell three-blade propeller are still being flight-tested before selection of the production unit.
Production has started, meanwhile, and Piper has increased its delivery plans for next year from 30 to 40 aircraft. Annual production of 60 Meridians is planned for 2001 and 2002, but the company is considering increasing output in 2001 to make more aircraft available sooner. The aircraft is sold out to July 2001.
The Meridian is being assembled on the same line as the Mirage's, and the manufacturing processes are unchanged. "When it was designed in 1984, the Malibu was a very advanced design," Emundson says of Piper's use of computer-aided design and manufacturing technology and metal bonding in the airframe. "It's a very efficient, strong design," he adds.
Amundson believes that the high-performance Meridian, because of its turbine engine and sophisticated systems, will be easier and safer to operate than the Mirage. Buyers will complete a week's training course, which will include use of a type-specific Meridian flight simulator.
Piper's design objectives for the Meridian were "performance, reliability and simplicity". The aircraft is aimed at the "owner-flown" business market, with buyers typically stepping up from the Mirage or coming from older piston and turbine twins. While the typical Meridian buyer "could afford a [Cessna] CitationJet with a professional pilot, they want to fly themselves", he says. "We have made it as easy to fly as possible."
Source: Flight International
